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Kristian Waagan updated DERBY-5090: ----------------------------------- Attachment: releaseNote.html Committed patch 3a to trunk with revision 1155332. Attaching the first attempt at a release note. > Retrieving BLOB fields sometimes fails > -------------------------------------- > > Key: DERBY-5090 > URL: https://issues.apache.org/jira/browse/DERBY-5090 > Project: Derby > Issue Type: Bug > Components: JDBC > Affects Versions: 10.7.1.1 > Environment: JDBC derby embedded driver > Reporter: Unai Vivi > Assignee: Kristian Waagan > Labels: BLOB, exception, null, read > Attachments: Derby5090.java, Derby5090_2.java, Derby5090_3.java, > derby-5090-1a-fix.diff, derby-5090-1a-fix.stat, derby-5090-1b-fix.diff, > derby-5090-2a-test.diff, derby-5090-2a-test.stat, > derby-5090-3a-change_messages.diff, releaseNote.html > > > This is my first issue report, so please be understanding if I'm posting the > wrong thing, in the wrong place or in the wrong way. I just want to help. :) > While iterating through a ResultSet, when accessing a BLOB field to read its > contents via an InputStream, I noticed that: > - if the current ResultSet's has been "warmed up" by retrieving another > column first, everything it's fine; > - if, on the other hand, you first-thing access the BLOB (and read other > columns later), then upon reading the first byte out the InputStream bound to > the BLOB field (ResultSet.getBinaryStream("col_name")) an IOException is > thrown (and IOException's getMessage() method returns null). > Following is an example, taken from a real application. The two code segments > only differ in the fact that a SMALLINT & VARCHAR read is done before/after > the BLOB read. > --Working snippet-- > [...] > icRelPath[i] = "imm" + File.separator + "ic" + "_" + > rs.getShort("setIcone") + "_" + i + "." + rs.getString("estensione"); > AutoCloseInputStream acis = new > AutoCloseInputStream(rs.getBinaryStream("ic" + i)); > if (rs.wasNull()) > icRelPath[i] = null; > else > { > //icRelPath[i] = "imm" + File.separator + "ic" + "_" > + rs.getShort("setIcone") + "_" + i + "." + rs.getString("estensione"); > BufferedInputStream bis = new > BufferedInputStream(acis); > int b = bis.read();//READS FINE > [...] > --Broken snippet-- > [...] > //icRelPath[i] = "imm" + File.separator + "ic" + "_" + > rs.getShort("setIcone") + "_" + i + "." + rs.getString("estensione"); > AutoCloseInputStream acis = new > AutoCloseInputStream(rs.getBinaryStream("ic" + i)); > if (rs.wasNull()) > icRelPath[i] = null; > else > { > icRelPath[i] = "imm" + File.separator + "ic" + "_" + > rs.getShort("setIcone") + "_" + i + "." + rs.getString("estensione"); > BufferedInputStream bis = new > BufferedInputStream(acis); > int b = bis.read();//THROWS IOException WITH A null > ERROR MESSAGE STRING > [...] -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira